1. Field of the Invention
The present invention relates to an articulated robot of which arm distal end is operated using preset track information, and a method for controlling the articulated robot.
2. Description of the Related Art
There has been an articulated robot of which arm constituted by a plurality of rotatably connected arm elements is driven to move an arm distal end to a predetermined position.
For example, a conveying apparatus that is a kind of an articulated robot described in Japanese Laid-Open Patent Publication No. 2011-167827 performs movement control of an arm distal end using track information generated in advance by a track information generating apparatus. Here, track information used for the movement control is generated based on a dynamics model of the arm so that moving time from a desired start point to a desired end point may be the shortest using an optimization technique.
Another articulated robot calculates in real time a path that interpolates between two given points with a straight line or a circular arc and performs driving control based on the calculated data instead of holding track information for driving in advance.
In a case where the track information po is generated in advance, the generated track information needs to be stored in a storage, and storage capacity of the storage must be increased to increase the number of tracks that the arm distal end of the articulated robot may follow. In a case where the track information is generated in advance, track calculation time for generating tracks is required, when the articulated robot is set up, depending on the number of pieces of track information to generate.
In a case where the conveyance path is calculated in real time, a relay point needs to be set by, for example, a teaching operation to connect the start point to the end point by a combination of a straight line or a circular arc, which is a time-consuming process. Further, even a skilled person has difficulty in setting a relay point that passes through an optimum path in consideration of many constraints, such as torque, the number of rotation, an angle, and acceleration of each axis. Further, since the articulated robot needs to perform interpolating calculation of the relay point, load is applied to a control unit of the robot.